JPS61282623A - Bearing unit - Google Patents

Abstract

PURPOSE:To reduce the abrasion of a bearing, by performing ceramic coating on a bearing plate formed of a steel plate, which supports the end of a shaft. CONSTITUTION:Ceramic coating 2 is performed on only a thrust bearing part, which a shaft 5 touches, of one-side surface of a bearing plate 1 formed of a steel plate, which is also used as a motor case. Such as a steel plate for porcelain enamel work or an aluminized steel plate, is used for the steel plate as a base material, and such as a wet dipping method or a wet spraying method is adopted as the coating method. In this way, the shaft can be rotate smoothly, as the abrasion resistance of the thrust bearing is raised.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a bearing device, particularly a thrust bearing device, used in a small motor serving as a tape drive source for, for example, a tape recorder or a videotape recorder.゛Prior Art In recent years, with the expansion of the home and industrial markets, the need for small motors to be lighter, thinner, and smaller has increased, and the development of ultra-small motors has been desired. This motor will be explained using an example of a coreless DC motor with reference to FIGS. 3 and 4.

In FIGS. 3 and 4, reference numeral 5 denotes a shaft having an arcuate tip, which is rotatably supported by a sleeve bearing 9 provided on a frame 11. As shown in FIG.

A plurality of molded windings 6 and a commutator 7 integrally molded from a plastic molded material 8 are attached to the shaft 5 to constitute a rotor. 12 is a magnet fixed to the frame 11 facing the shaped winding 6; 13 is a yoke facing the magnet 12 via the shaped winding 6; 14 is a brush with a sliding contact on the commutator 7; 15 is the frame 1
A thrust bearing 10 for receiving the tip of the shaft 5 is installed at the center of the inner bottom of the bracket.

In the above configuration, the shaft 5 is supported by a radial bearing 9, and when it rotates, the load in the thrust direction is transferred to the thrust bearing 1.
It is structured so that it can be received at 0. At this time, thrust bearing 1
For example, the load received by 0 is 10 to 600 gr in a system that uses magnetic force to take away the thrust load to prevent the rotor from moving up and down, and in the case of a shaft with a diameter of 1 to 2 mm. The diameter of the thrust bearing contact portion at the tip is approximately 092 mm, and the load per unit area is 0.
3 to 20 Kg f/cm". The thrust bearing 10, which receives the load and rotates at high speed, is extremely prone to wear. Therefore, in order to compensate for the wear resistance of the thrust bearing 10, a hard material such as partially stabilized zirconia or the like is used. If the bearing is made of ceramic such as silicon carbide or alumina, there will be problems such as the steel shaft wearing out or the ceramic bearing cracking due to impact.Cracking of ceramic due to impact can be solved by increasing the thickness of the ceramic itself. I can't satisfy the needs of frivolous, short, and small.

The following table shows examples of materials used in conventional thrust bearings and examples of their various characteristics.

The test conditions in Table 1 and Table 2 are as follows: 1. Test temperature: room temperature 2, rotation speed: 2200 rpm3, rated output
:O, IW 4, Voltage? 4.2V 5, current value: 100mA.

As a result of the above, an excellent bearing material is desired.

Problems to be Solved by the Invention The present invention aims to reduce wear caused by sliding between the shaft and thrust bearing of a small motor, and at the same time reduce wow and flutter, reduce power consumption, and reduce vibration noise. The aim is to improve performance such as:

Means for Solving the Problems In order to solve the above problems, the present invention provides a thrust bearing in which a ceramic coating is applied to one or both sides of a steel bearing plate.

Effect: By the above means, the life of the motor can be extended without causing mutual wear between the shaft and the bearing.

In addition, the sliding properties of the bearing are improved, and performance can be improved, and a design that is light, thin, short, and small becomes possible.

Example FIG. 1a shows an embodiment of the invention.

In addition, except for the thrust bearing, the configuration is the same as the conventional one.
The explanation will be omitted. In the figure, reference numeral 1 denotes a bearing plate made of a steel plate that also serves as a motor case, and a ceramic coating 2 is applied only to the thrust bearing portion on one side of the bearing plate that the shaft 5 comes into contact with. Grease 4 is applied to this sliding surface.

FIG. 2 shows a steel plate with a ceramic coating 2.3 on both sides, which is useful when there is a concern that the steel bearing plate 1, which also serves as a motor case, may be corroded. Note that the bearing of the present invention does not have a surface hardness that is significantly different from that of the shaft like conventional ceramic bearings, but rather
If the hardness is 5 US420J and 650 Wits force), select one with a hardness of 850 to 950 from among those with a hardness of 650 to 750. The surface roughness is set to 0.1 to 2.0 μm, and the sliding surface is coated with grease.

In addition, the following materials and coating methods are used for the bearing plate 1.

1. The steel plate as the base material is a) Steel plate for crawlers b) Aluminized steel plate c) SO3 steel plate d) Use other steel plates.

2. The coating method is a) Wet depping method b) One-way wet spray C) Dry powder coating method d) Dry electrostatic coating method etc.

The test conditions in the previous table are: 1. Test temperature: normal temperature 2. Rotation speed: 2200 rpm3, rated output
:Q, lW 4, Voltage: 4.2V 5, Current value: 100mA.

6. Bearing 1 of the present invention: Vickers hardness 650-75
0Hv.

7. Bearing 2 of the present invention near 50 to 850 Hv.

8. Bearing 3 of the present invention: 850 to 950 Hv.

As an example of the composition of the frit for ceramic coating, those shown in the table below can be used.

Table 4 Effects of the Invention As is clear from the above description, the present invention provides the following effects.

1) Improved wear resistance of the thrust bearing enables smooth rotation and long life.

2) There is no formation of recesses due to the wear of the thrust bearing, and the phenomenon of the rotor dancing up and down due to minute movements of the shaft is eliminated, making it possible to obtain an excellent motor with low levels of vibration and noise.

3) As a result of 2), wow and flutter can also be reduced.

4) Because the surface of the thrust bearing is smooth for a long time,
It is possible to reduce power consumption and obtain an energy-saving type motor.

5) Since the ceramic coating is applied to the steel plate base, a thrust bearing with excellent impact resistance can be obtained.

6) Since a thin ceramic coating layer is sufficient, it is possible to obtain a thrust bearing that can be made lighter, thinner, shorter and smaller.

7) If the steel plate for ceramic coating is a base that is susceptible to corrosion, coating can be applied on both sides to obtain a thrust bearing with greater corrosion resistance.

8) The ceramic coating surface is microscopically porous and can retain the applied grease for a long period of time, contributing to extending the life of the thrust bearing.

As a result of 1) to 8) above, the quality of the small motor has been improved and its life has been significantly extended, and a motor with a light, thin, short and small design has been realized.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a motor showing a first embodiment of the present invention;
FIG. 2 is a sectional view of a bearing plate according to another embodiment of the present invention;
FIG. 3 is a sectional view of a conventional motor, and FIG. 4 is a perspective view showing the configuration of a general rotor. 1... Bearing plate, 2, 3... Ceramic coating, 5... Shaft.

Claims (5)

[Claims] (1) A bearing device characterized in that a ceramic coating is applied to a steel bearing plate that supports the tip of a shaft. (2) The bearing device according to claim 1, wherein the bearing plate is constituted by a motor case and is coated with a ceramic coating at least on the portion that comes into contact with the tip of the shaft. (3) The bearing device according to claim 1, wherein the bearing plate is constituted by a motor case, and both sides of the motor case are coated with ceramics. (4) The bearing device according to claim 1, wherein the surface hardness of the ceramic coating is 0 to 300 Hv harder than the hardness of the shaft. (5) The surface roughness of the ceramic coating should be 0.1~
Claim 1 characterized in that the diameter is 2.0 μm.
Bearing device as described in section.